Chemical vapor deposition methods are employed to form films of material on substrates such as wafers or other surfaces during the manufacture or processing of semiconductors. In chemical vapor deposition, a chemical vapor deposition precursor, also known as a chemical vapor deposition chemical compound, is decomposed thermally, chemically, photochemically or by plasma activation, to form a thin film having a desired composition. For instance, a vapor phase chemical vapor deposition precursor can be contacted with a substrate that is heated to a temperature higher than the decomposition temperature of the precursor, to form a metal or metal oxide film on the substrate. Preferably, chemical vapor deposition precursors are volatile, heat decomposable and capable of producing uniform films under chemical vapor deposition conditions.
The semiconductor industry is currently considering the use of thin films of various metals for a variety of applications. Many organometallic complexes have been evaluated as potential precursors for the formation of these thin films. A need exists in the industry for developing new compounds and for exploring their potential as chemical vapor deposition precursors for film depositions.
For the chemical vapor deposition of silicon-containing films (e.g., SiO2), compounds such as silane, chlorinated silanes, and alkoxy silanes (e.g., TEOS) are well known. However, as next generation oxide materials with higher dielectric constants, so called ‘high-k’ materials (e.g., HfO2), are integrated, and concurrently new precursors are developed for these materials (e.g., hafnium amides), other silicon precursors will require development for the deposition of ternary systems and beyond (e.g., hafnium silicates).
For silicon amide compounds with cyclic amide ligands, an example reported in the literature is tetrakis(pyrrolidinyl)silane (a solid at room temperature, mp=30° C.). Inorg. Nucl. Chem. Letters 1969 5 733 discloses tetrakis(pyrrolidinyl)silane compound and a low yield synthetic method for preparation thereof.
U.S. Patent Application Publication Nos. US 2002/0187644 A1 and US 2002/0175393 A1 disclose metalloamide precursor compositions having stated utility for forming dielectric thin films such as gate dielectric, high dielectric constant metal oxides, and ferroelectric metal oxides and to a low temperature chemical vapor deposition process for deposition of such dielectric thin films utilizing the compositions.
A need exists in the industry for an improved silicon dioxide atomic layer deposition precursors. Although many silicon precursors are readily available (e.g., silane, tetrachlorosilane, tetraethoxysilane, tetrakis(dimethylamino)silane), none of these silicon precursors have the desired optimal properties of an atomic layer deposition precursor for certain applications. One of these applications is for a nanolaminate structures in tandem with other materials, for example a high-k material such as HfO2. For this application, a balance of reactivity and thermal stability must be achieved to grow self-limiting SiO2 with an adequate growth rate. Compounds such as silane may be too unstable, tetrachlorosilane may yield halogen impurities, and tetraethoxysilane and tetrakis(dimethylamino)silane may be too unreactive within the temperature parameters of the application. The problem is therefore to generate a suitable atomic layer deposition precursor for such an application.
Further, in developing methods for forming thin films by chemical vapor deposition or atomic layer deposition methods, a need continues to exist for precursors that preferably are liquid at room temperature, have adequate vapor pressure, have appropriate thermal stability (i.e., for chemical vapor deposition will decompose on the heated substrate but not during delivery, and for atomic layer deposition will not decompose thermally but will react when exposed to co-reactant), can form uniform films, and will leave behind very little, if any, undesired impurities (e.g., halides, carbon, etc.). Therefore, a need continues to exist for developing new compounds and for exploring their potential as chemical vapor or atomic layer deposition precursors for film depositions. It would therefore be desirable in the art to provide a precursor that possesses some, or preferably all, of the above characteristics.